Tag Archives: cats and dogs

A close up look at how our dogs drink…

The field of fluid dynamics explains how our dogs drink and why they splash and slop more than cats…

The drinking mechanism of a dog is videotaped from three different angles (A, B, and C). The curved tongue is rapidly withdrawn and a water column is formed underneath. A physical experiment is designed to understand and characterize the underlying fluid mechanics.  Photo by:  Sean Gart and Sunghwan (Sunny) Jung/Virginia Tech

The drinking mechanism of a dog is videotaped from three different angles (A, B, and C). The curved tongue is rapidly withdrawn and a water column is formed underneath. A physical experiment is designed to understand and characterize the underlying fluid mechanics. Photo by: Sean Gart and Sunghwan (Sunny) Jung/Virginia Tech

By studying the drinking habits of various dog breeds and sizes, a group of researchers at Virginia Tech and Purdue University has recently identified and modeled the fluid dynamics at play when dogs drink water.

“Three years ago, we studied how cats drink,” said Sunny Jung, an assistant professor at Virginia Tech. Jung’s research focuses include biofluid mechanics and the nonlinear interactions between soft bodies and surrounding fluids. His current project is sponsored by the National Science Foundation’s Physics of Living Systems program. “I was curious about how dogs drink, because cats and dogs are everywhere.”

As members of the order Carnivora, cats and dogs have incomplete cheeks, which allow them to open their mouths wide to deliver killing blows. But what makes pack hunting possible also makes suction drinking impossible. Unable to seal their cheeks completely, there is no way for a dog to suck up water. Conversely, humans have “complete” cheeks, and we drink by creating negative pressure, allowing us to suck water into our mouths and down our throats.

Cats, too, lack suction, and they compensate by drinking via a two-part “water entry-and-exit” process. This consists of a plunging and a pulling phase, in which a cat gently places its tongue on the water’s surface and then rapidly withdraws it, creating a column of water underneath the cat’s retracting tongue.

“When we started this project, we thought that dogs drink similarly to cats,” Jung said. “But it turns out that it’s different, because dogs smash their tongues on the water surface — they make lots of splashing — but a cat never does that.”

When dogs withdraw their tongue from water, they create a significant amount of acceleration — roughly five times that of gravity — that creates the water columns, which feed up into their mouths. To model this, Jung placed cameras under the surface of a water trough to map the total surface area of the dogs’ tongues that splashed down when drinking.

The researchers found that heavier dogs drink water with the larger wetted area of the tongue. This indicates that an allometric relationship exists between water contact area of the dog’s tongue and body weight – thus the volume of water a dog’s tongue can move increases exponentially relative to their body size.

In order to better understand how the physiology works, Jung and his colleagues could only go so far by watching dogs drink. They had to have the ability to alter the parameters and see how they affected this ability, and since they could not actually alter a dog in any way, they turned to models of the dog’s tongue and mouth. “We needed to make some kind of physical system,” Jung said.

For their model, Jung and his colleagues used glass tubes to simulate a dog’s tongue. This allowed them to mimic the acceleration and column formation during the exit process. They then measured the volume of water withdrawn. They found that the column of water pinches off and detaches from the water bath primarily due to gravity. Dogs are smart enough to close their mouth just before the water column collapses back to the bath.

Source:  Newswise media release

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Robin Williams leaves behind family and pug, Leonard

As the world learns more about the tragic loss of actor and comedian Robin Williams to suicide, this journalist from the Dog Channel has written about Williams and his Pug, Leonard.

I am sure that Leonard is mourning the loss of his doggy dad and owner today.

Rest easy, Mr Williams.

Robin Williams Leaves Behind Family and Pug, Leonard

Doggy quote of the month for September

Once when I had remarked on the affection quite often found between cat and dog, my friend replied, ‘Yes.  But I bet no dog would ever confess it to the other dogs.’

–  C.S. Lewis

Cat-and-Dog

It’s raining cats and dogs

It’s been raining since last night here and the long-range forecast is that it will continue for the next few days.  And so that has gotten me thinking – what is the origin of the saying It’s raining cats and dogs?

On the face of it, this phrase just doesn’t make sense.  Some say that it comes from the days when all the animals in the household were kept in the rafters of the thatch-roofed cottages.  When it really rained heavily, the animals would fall out…

What does the Library of Congress say about this phrase (including de-bunking of the thatched roof theory)?

Read here for a well-referenced look at the origin of It’s raining cats and dogs